In this type of vehicle, there is an apparatus for dealing with a voltage drop of a battery functioning as a power supply source for the rudder angle varying device (refer to a patent document 1). According to a vehicle steering control apparatus disclosed in the patent document 1, when it is detected that the voltage of the battery is less than or equal to a predetermined driving device fixed voltage, a rotation angle of the VGRS as a driving device is fixed. Moreover, after that, when it is detected that a wheel (also referred to as a steering wheel) is turned back, a deviation between a neutral position of the steering wheel and a vehicle straight-ahead driving position, which occurs when the rotation angle of the driving device is fixed, is corrected. Thus, it is believed that it is possible to correct the deviation between the neutral position of the steering wheel and the vehicle straight-ahead driving position while suppressing a load of the battery.
Incidentally, there is also suggested an apparatus for performing a neutral position return on left and right wheels in a period between an ignition off, in which electric power is ensured, and an engine stop (refer to a patent document 2).
Moreover, there is also suggested an apparatus for suppressing an output of the EPS at multiple steps in the voltage drop (e.g. refer to a patent document 3).